Distillation of resin



July 27 1926.

F. GREENWOOD DISTILLATION OF RESIN Filed August 25 Y v m w v Q a m .R\ x Tw i a fo m Fw /w Patented July 27, 1926.

UNITED STATES.

PATENT- OFFICE:

- 3mm: E. eanmqwoonor m'zw ROCHELLE, new YORK, ASSIGNOR 'ro PINE WASTE rnonue'rs, me, or NEW YouK, N. Y., A oonronarron or DELAWARE."

DISTILLATION .OF RESIN.

. Appllcationflled August 25, 1920." Serial No. 405,923.

' The present invention relates to the recover of rosin and rosin oils from. the socalle rosin soap derived from'the black liquor of pulp mills. tains various acid resins, as their sodium salts or resinates, as-well as various neutral resins and terpenes' emulsified thereby.

Heretofore, this rosin soap, though containing a good proportion of real rosin, as wel as many other resins, has been generally considered and treated as a waste product. I

The objects, of my invention are to utilize this rosin soap and to provide a commercially feasible and economical method and suitable apparatus for extracting these valuable' resinous products.

According to an advantageous method the rosin soap is obtained from the pulp mill black liquor by a separation Process, involving usually simply a skimming operation, in which advantage is taken of the fact that the rosin soap being lighter, rises to the surface of the pulp mill black liquor and can then be removed by simply skimming it off the top. After such separation the rosin soap, is first treated with an acid (for instance, sulphuric) to transform the alkali resinates and set free their acids. This product is then heated and subjected to the action of superheated steam. The steam exerts a selective distilling efl'ect, separating the rosin and rosin oils from other matters contained in the rosin soap. The extracted matter is suitably collected as by means of a series of condensers.

In the accompanying drawing I have illustrated more or less dia rammatically (a form of apparatus designe for thepractice of the' invention, but as this illustration is primaril in the nature of a flow sheet in tended or the purposes of disclosure, I would have itunderstood that the irivention is not limited to this particular form of apptaratus.- v r the illustration, 1 designates a furnace or heater, 2 a superheater coil, 3 a retort in the nature of a still, 4, 5 and 6 a series of air condensers, and 7 a water cooled, condenser.

The rosin soap after acidification and separation of the aqueous solution of salts, or of some oil this solution, is charged into the retort 3, as by means of a supply hopper This material con- 8 which maybe steam or otherwise heated to cause the crude resinous matter to feed into the retort.

The retort is externally heated as bybeing encased within a chamber 9 receiving the waste gases from the furnace, the ,arrows in the illustration indicating the direction of flow to and about the retort.

In similar fashion, the air cooled condensers are shown as encased in chambers 10, 11 and 12 forming continuations of the Waste gas conduit. The heating of these condensers is preferably controlled to prevent condensation of the steam, while permitting condensation of the products which it is desired to collect. The selective control of the heat in the several chambers is obtained .in the illustration by means of cold air inlet dampers 13, 14 and 15, and by means of a suction fan 16 applied to the outlet :of the last condenser chamber. This fan is shown as driven by a variable speed motor 17, and therefore as capable of beingregulated'to vary the flow through the retort and condenser chambers. By regulating this flow and the several cold air inlets, the temperatures in the several chambers may be accurately governed.

The steam from the superheater coil is admitted into the bottom portion of the retort through a perforated pipe 18. The retort and the condensers are connected in series by the successive connections indicated at 19, 20, 21 and 22.

The temperature .of the retort chamber is controlled by governing the heat of the furnace and is further shown as controlled by means of a cold air inlet damper 23 and an exhaust fan 24 which may be used to bypass the heat away from the chamber.

Thermometersare shown at 25, 26 and 27 for indicating the temperature of the superheated steam, the temperature within the retort and the temperature of the retort chamber. I have also shown thermometers at 28, 29 and 30 for indicating the temperatures in the respective air condensers.

At the proper temperature, distillation takes place and the vapors of resin and rosin -oilare carried from the retort over to the tile and dark colored contaminating prod-- steam, which was at slightly above atmospheric pressure, was heated to 340 C.

The temperature of the first condenser is controlled to cause the rosin which has the highest boiling point to deposit there by condensation and to cause the oils having lower boiling points-to be carried on to the next condenser. This heat :also is suflicient to prevent condensation of the steam at this point.

B the proper control of the temperature in the successive condenser, chambers, rosin oils of varioiis boiling points can be selectivel condensed and collected, the steam and ow boiling oils be ng finally condensed in the water cooled condenser at the end of the apparatus. 7

With this improved process and by meansof the apparatus disclosed, I have obtained from the first condenser a good grade commercial light-colored rosin, and

from the other condensers valuable rosin.

oils of difierent boiling points.

tively in t at it carries oil the more. volatile resin acids, which may be here called abietic acid, of the resin soap, leaving the less volaucts as a residue. The .more volatile abietic acid is thus in effect volatilized by the steam away from the contaminating products and is condensed in a purified condition. The residue may be drained from the retort, as required, by a suitable outlet drain, as indicated at 31.

In a companion application of mine filed of even date herewith, Serial No. 405,921, I have disclosed what is known as the plural-solvent method of extracting the valuable resinous constituents from rosin soap. In that method the rosin soap is first mixed with a solvent, such as gasoline, which is immiscible with water an d which does not dissolve the soap but forms an emulsion therewith. To this emulsion there is added a mineral acid, such as sulphuric, which liberates abietic acid etc. and enables absorption by the solvent. This solvent carrythe abietic acid as well as certain 1n otfier bodies which it is desired to separate from the abietic acid, is then mixed with a second solvent, such as alcohol, which is immiscible with the first and in which the abietic acid is readily soluble. This second solvent operates selectively to remove the abietic acid content from the first solvent and the refining process is usuall continued by mixing resh portions of t e second solvent with the first solvent until a point is reached where fresh additions of the secof the solvents of my other application with the superheated steam for the purpose of directly extracting the abietic acid, or in other words, "the rosin-and rosin oils therefrom.

This modification simply involves the substitution in the retort of the residue .obtained from the solvents for the crude resins of the rosin soap, as heretofore described, the operations and effects being generally similar.

I am aware that it has been proposed to refine certain entirely different materials, the various grades of commercial rosin by a steam treatment. This is disclosed in the United States patent to Hunt & Pochin, N0. 22,558, January 1, 1859, but the present invention relates to the steam treatment of something else, the resinous matters recovered from black liquor.

What I claim is:

l. The process of recovering resin and the products thereof from pulp mill black liquor which comprises separating rosin soap from said li uor, treating said soap with a solvent an an acid, treating the resultant solution with a second solvent im miscible with the first, separating the solutions, evaporating the-solvent from the second solution and subjecting the residue from the second solution to distillation in the presence of superheated steam.

2. The process of recovering resin and the products thereof from pulp mill black liquor which comprises separating rosin soap from said li uor, treating sa1d soap with a solvent an resultant solution with a second solvent immiscible with the first, separating the solutions, evaporating the solvent from the second solution, subjecting the residue from the second solution to distillation in the presence of superheated steam, and condensing the distillate in successive stages.

In witness whereof, I have hereunto set my hand this 23rd day of August 1920.

FRANK E. GREENWOOD.

an acid, treating the 

